We have developed the technique of subtractive hybridization as a powerful tool for isolating clones of mRNAs that are restricted to anatomically-defined subsets of neurons. Using this technique we have isolated the product of the rds neuronal degeneration gene. We propose studies to test a model for its function as an intralumenal adhesion molecule, to improve our understanding of the disposition of the rds protein in the outer segment disc membrane, to prove that inactivation of the rds protein is solely responsible for the rds phenotype, and to understand fully the nature of the rds mutagenic event and mutant protein expression. We have also isolated clones of mRNAs encoding a telencephalon-enriched, calmodulin-binding substrate for protein kinase C and a telencephalon-enriched Ca++, calmodulin-dependent protein kinase. To interpret the physiological significance of each, we will map their genes so as to learn whether they are the products of any known gene for which mutants have been characterized and we will also produce deliberate mouse mutants affected in their expression. To this end, we will develop ribozyme and homologous recombination gene knock-out methodologies. We will produce recombinant proteins for biochemical assessments of function, including proof that the kinase truly has that activity and a search for its natural substrates. We will investigate amino acid sequences that direct proteins to dendrites.